  <link rel="stylesheet" type="text/css" href="common/css/header.css">
  <div class="header">
           <div class="header_left">
                  <a href="index.shtml"><img src="images/logo.png" class="logo"></a>
           </div>
           <div class="header_right">
                  <ul id="top_nav">
                       <li id="index"><a href="index.shtml">首页</a></li>
                  </ul>
           </div>          
     </div>